LabLearner Discussion: Germs
The good news is that our skin is resistant to viruses. There are no receptors for viruses to bind to on our skin. In addition, the outer layer of our skin, the epidermis, is actually composed of dead skin cells that are constantly being shed and viruses are shed with them. The bad news is that there are three major paths that viruses can take to enter our bodies and start an infection. Viruses need to enter the body through contact with a mucous membrane. The mucous membranes that are easily accessible to viruses on the outside of our bodies are in the eyes, nose, and mouth.
In the first part of the COVID-19 LabLearner Discussions series (Large and Small), we established the concept of larger and smaller. We discussed that there are real things, not invisible or imaginary things, that are simply too small to see. This is a very important point for children to grasp. There is no point in further discussion if the child doesn’t believe germs exist simply because they can’t see them.
In this LabLearner Discussion, we will begin by discussing some of the many types of microbes and end by considering how germs can be spread and how they can enter our bodies. This will lead into the final LabLearner Discussions in the COVID-19 series, Hands Off!, in which children will learn much more about how to stop the spread of germs and how to kill them by properly washing their hands.
Germs are not invisible. They are just too small to see without a microscope. This concept serves as a link for your child back to where the first LabLearner Discussion left off. Begin this LabLearner Discussion with a very brief review of the preceding one, including: 1) objects can be very large or very, very small, 2) microscopes make very small objects visible, and 3) the cells in our bodies, including our blood cells, are much smaller than even a single grain of sand.
This slide shows a scientist or doctor using a microscope. It is a light microscope, meaning that light is passed up through the specimen and into glass lenses that magnify the image. For very young children, differentiating between types of microscopes may be confusing. Just refer to these instruments as microscopes.
The essential point of this slide is that there are many different kinds of germs. Discuss with your child the concept that, while there are many different sizes, shapes, and uses for balls, all of them are nonetheless referred to as balls. In a similar manner, we often refer to all microscopic organisms as germs.
You may also discuss that there is more than one name for “germs” including microorganisms, microbes, and as shown in this slide, viruses, protozoans, and bacteria. Disease-causing germs are frequently also called pathogens and finally, the informal term bugs is often heard among scientists when referring to germs!
In this slide we simply wish to illustrate that not all of microbes are harmful. We have restricted examples here to those which children might reasonably be familiar with. In these examples, the yogurt, cheese, pickles, and olives require bacteria to be made. Producing wine and bread require another microbe that we won’t discuss further here, called yeast.
There are many other helpful uses of microbes including single-cell plants. For example, sewage treatment requires microbes, as does ethyl-alcohol production through fermentation as an additive in gasoline. Microorganisms will likely become more important for alternative forms of energy production in the future.
Germs are far from all being good and useful to humans! This slide points to a few examples of harmful effects of germs. In the current context, disease-causing germs are the most relevant.
This slide shows just a few of the many different kinds of bacteria that cause disease in humans. Streptococcus pneumoniae is the genus (Streptococcus) and species (pneumoniae) name for a bacterium (singular for bacteria) that causes pneumonia in humans. Clostridium is a bacterium that causes botulism. The bacterium Clostridioides difficile causes intestinal inflammation and diarrhea.
We have finally arrived at the viruses. Viruses cause many notorious childhood diseases. Each of the viral diseases shown here, with the unfortunate exception of coronavirus (COVID-19), can be prevented by a vaccine. Vaccines work by stimulating the host’s (the patient’s) own immune defense system to recognize a specific virus (or bacteria) and target them for destruction by the body. We do not currently have a vaccine for the new COVID-19 virus as it has just surfaced in the human population. Many laboratories are feverishly working to produce such a vaccine and it will certainly be forthcoming as quickly as possible.
It is worth pointing out that the brightly colored virus pictures in this slide and the bacteria in the previous slide are artificially colored and may represent composite reconstructions. Viruses are only visible in the electron microscope, which produces black and white images.
This slide illustrates one of the most common ways by which a virus is spread from an infected person – sneezing and coughing. Your child has almost certainly been told to “cover their face” when they cough or sneeze. This is because the mist and droplets expelled during a cough and particularly a sneeze can be loaded with viruses and be projected into the air for some distance.
In the next LabLearner Discussion in this COVID-19 series, we will learn more about the distance that viruses can travel in a sneeze. Also, it is worth noting that sneezing or coughing into one’s hand is not as safe as into the inside of the bent elbow. This is largely because, once on our hands, the virus can be transferred to others through direct touching (hand shaking, for example) or handling items that others may touch and become infected.
This simple slide accentuates the point that a sneeze, in addition to actually spraying another individual with viruses, can spread them to other surfaces. The new COVID-19 virus, for example, can last from several hours to days on various surfaces. Therefore, once a virus has been deposited on a surface like a doorknob, subway or stairway railing, table, or other surface, it can subsequently be transferred to the hands of another individual who touches that surface later.
As suggested, you may ask your child, “Are there any other places viruses might land when someone sneezes?” The discussion that follows should help your child realize that viruses and other harmful microbes could be on any surface they touch.
This slide asks your child the question “How could viruses get on your hands?”. Discuss with them that by touching objects that a virus has been sprayed on or in any way transferred to (for example, an infected person sneezes into their hand and then grabs a doorknob or shopping cart handle), that viruses can then be transferred to their own hands. This is the rational for wiping surfaces with sanitizers before touching them.
The good news is that our skin is resistant to viruses. There are no receptors for viruses to bind to on our skin. In addition, the outer layer of our skin, the epidermis, is actually composed of dead skin cells that are constantly being shed and viruses are shed with them.
The bad news is that there are three major pathways that viruses can take to enter our bodies and start an infection. Viruses need to enter the body through contact with a mucous membrane. The mucous membranes that are easily assessable to viruses on the outside of our bodies are in the eyes, nose, and mouth. This is why we are told not to touch our faces when there is an epidemic. Viruses on our hands (which are covered with skin) can’t enter our bodies unless we touch our face because it is there that the eyes, nose, and mouth are located.
This final slide ends with the recommendation that you and your child discuss ways to stop viruses from entering their body. Have them consider all of the information included in the preceding slides and use critical thinking to make suggestions. These might include ideas like cover your mouth in your sleeve when you sneeze, sanitize (clean) surfaces before touching, and NOT touching their face if they are not sure if their hands are virus-free.
Stopping the spread of germs and killing germs with good hand-washing techniques will be the main emphasis of the next LabLearner Discussion, Hands Off!
Germs: Relevant LabLearner CELL Curriculum Units
Health and Hygiene
The Human Body
Microscopes & Magnification
Light & Optics